LM7805ACT - 5V 1A Fixed LDO Regulator, TO-220 | onsemi
MPN: LM7805ACT ✓ Hoạt độngLM7805ACT Tóm tắt
A linear regulator (LDO - Low-Dropout) is a type of voltage regulator that maintains a stable, low-ripple DC output even as the input voltage varies, by dissipating the excess voltage as heat across a pass element. Within the broader system hierarchy, the LM7805ACT sits in the linear-regulator branch of the power-management IC family, and is favored over switching regulators whenever the application values noise-free output, simplicity, low BOM cost, and fast transient response over efficiency. The 78xx series is the de-facto industry baseline for 5 V, 12 V, and 15 V analog rails.
Key features include a 1 A continuous output rating (with peak inrush capability higher for short transients), ±2% output voltage tolerance (the "A" grade, versus ±4% on the non-A version), 2.0 V typical dropout at full load, internal short-circuit current limit, thermal-overload protection, and a TO-220 tab that doubles as the thermal pad. No external components are required beyond input and output bypass capacitors (typically 0.33 µF and 0.1 µF).
The device uses a vertical NPN pass transistor architecture with a bandgap reference, Zener-based trimming, and on-chip safe-operating-area compensation. The architecture is intentionally simple - it has no enable pin, no soft-start, and no power-good flag - because the 7805 was designed as a "set-and-forget" rail for analog and digital subsystems where it can be left always-on behind a master switch. Its primary limitation is dropout (cannot produce 5 V from a 5 V rail) and efficiency (Pdiss = (VIN − 5 V) × IOUT, all of which becomes heat).
Typical applications include 5 V digital logic supplies, microcontroller and sensor power, hobby/Arduino/Maker boards, USB device supplies, op-amp and ADC reference rails, replacement of legacy linear rails, and any application where a clean, low-noise, fixed 5 V rail is needed from a higher-voltage DC bus.
Design consideration: at 1 A load the LM7805ACT dissipates approximately 7 W when dropping 12 V to 5 V, which demands a heatsink rated for at least 10 °C/W or larger copper area on the TO-220 tab. Always place input/output ceramic bypass capacitors close to the pins and respect the SOA of the internal pass transistor at high VIN.
This page synthesizes live distributor pricing, parametric drop-in alternatives across onsemi, STMicroelectronics, Microchip, and TI, and practical thermal/layout design notes that go beyond what is in the manufacturer datasheet.
Bộ thay thế dễ dàng lắp đặt cho LM7805ACT — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
Các biến thể trong loạt này
Các mẫu cùng loạt có thể lắp đặt dễ dàng tương thích với LM7805ACT (cùng hình factor và footprint) — khác nhau ở Dropout Voltage, Input Voltage Range, Maximum Output Current, Mounting Type, Output Voltage.
MC7805ACTG
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
L7805CV
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →MC7805CTG
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
MC7805BTG
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
UA7805CKCS
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
LM7805ACT Tỷ lệ tối đa & tính chất điện
| Regulator Type | Linear, Fixed Positive |
| Cấu trúc | 3-terminal LDO (78xx family) |
| Điện áp đầu ra | 5.0 V nominal |
| Output Voltage Tolerance | ±2% (A-grade) |
| Điện áp tối đa đầu ra | 1.0 A continuous |
| Phạm vi điện áp đầu vào | 10 V to 35 V |
| Điện áp mất áp | 2.0 V typical at 1 A |
| Nhiệt độ mối nối hoạt động | -40 °C to +125 °C |
| Internal Protection | Thermal shutdown, internal current limit, safe-area compensation |
| Hộp | TO-220-3 (TO-220AB), through-hole, 3 pins + tab |
| Pinout | Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output (front view, tab up) |
| Kiểu lắp đặt | Through-hole (THT) |
| Trạng thái RoHS | Compliant |
| Lead-Free | Yes |
| Cấp MSL | N/A (through-hole package) |
Cấu hình chân LM7805ACT
| Chân 1 | VIN — Input voltage (10 V to 35 V) |
| Chân 2 | GND — Ground (tab also internally connected to GND) |
| Chân 3 | VOUT — Regulated +5.0 V output |
Ứng dụng tiêu biểu
LM7805ACT phù hợp cho 6 Áp dụngs: Microcontroller and Arduino Power Rail, Sensor and Analog 5 V Supply, USB Device and Charging Supply (5 V), Industrial 24 V Bus to 5 V Logic, Hobby and Replacement / Repair Applications, Automotive Accessory and Aftermarket 5 V Supply.
Microcontroller and Arduino Power Rail
The LM7805ACT is the canonical 5 V regulator for microcontroller boards, including Arduino Uno/Mega clones, PIC and STM32 dev boards, and standalone MCU designs. With its fixed 5 V output, ±2% tolerance, and 1 A current capability, it can power an ATmega328 plus typical peripherals (LEDs, LCD, logic-level sensors) without a heatsink at light load. The 10-35 V input range means it can be fed directly from a 9 V wall adapter, a 12 V lead-acid battery, or a 24 V industrial bus. Place 0.33 µF at VIN and 0.1 µF at VOUT close to the IC pins to suppress switching transients from upstream DC-DC stages and digital logic. Because the regulator dissipates (VIN − 5 V) × IOUT as heat, expect ~1 W at VIN = 9 V, IOUT = 250 mA - small enough for the TO-220 tab to self-dissipate.
Được đề xuất
Sensor and Analog 5 V Supply
Precision sensors, op-amps, and ADCs benefit from the LM7805ACT's clean, low-noise linear output - no switching ripple - which preserves measurement integrity. With 5.0 V ±2% and PSRR sufficient for sensor bandwidths, it can power instrumentation amplifiers, strain gauge bridges, and 5 V op-amp rails. The fixed 5 V output is convenient for ratiometric sensors where the regulator's output also serves as the ADC reference. At modest sensor loads (typically 10-100 mA) the part dissipates < 1 W and runs cool without a heatsink. The 10-35 V input range lets a single regulator serve both 12 V and 24 V industrial systems.
Được đề xuất
USB Device and Charging Supply (5 V)
For USB-powered devices, dongles, and simple charging circuits, the LM7805ACT can be used as a clean 5 V source from a higher-voltage battery or wall adapter. The fixed 5 V matches the USB VBUS nominal exactly, and the 1 A rating covers most USB device requirements. Unlike a switching regulator, the linear output adds no EMI near the USB data lines (DP/DN) - important for full-speed and high-speed signaling. Place a common-mode choke upstream and the 7805 downstream to combine clean power with EMI filtering. Note that the dropout prevents 5 V-to-5 V operation; this topology requires VIN ≥ 7 V.
Được đề xuất
Industrial 24 V Bus to 5 V Logic
Factory automation, PLCs, and industrial control boards frequently need a local 5 V rail generated from a 24 V nominal bus (which can be 22-28 VDC). The LM7805ACT is rated to 35 V input, easily handling the worst-case 24 V bus plus tolerance. At 24 V in and 5 V out, dissipation at 1 A is 19 W - significant, so a heatsink rated for ≤ 5 °C/W is required. This is the textbook 78xx application: rugged, simple, fault-tolerant. The internal thermal shutdown protects the part if the heatsink falls off, and the internal current limit protects downstream shorts.
Được đề xuất
Hobby and Replacement / Repair Applications
The LM7805ACT is the most-replaced linear regulator in hobby electronics, repair shops, and educational labs - it is the 5 V output every textbook, lab manual, and YouTube tutorial assumes. When repairing vintage equipment, retrocomputing mods, or DIY synth/guitar pedal circuits, dropping a TO-220 7805 into a 3-pin 78xx footprint gives a known-good 5 V rail in seconds. It is also a popular "reference rail" on breadboard power supplies, bench supplies, and bench-top prototyping kits. With its ±2% A-grade tolerance, the ACT version is preferred over the cheaper CT (±4%) for analog work where 5.0 V accuracy matters.
Được đề xuất
Automotive Accessory and Aftermarket 5 V Supply
In automotive 12 V battery systems, the LM7805ACT can supply 5 V to aftermarket accessories, dashcams, GPS units, lighting controllers, and telematics modules. The 10-35 V input range covers the full automotive transient envelope (cold-crank to load-dump) within operating limits. At 13.8 V VIN, 5 V VOUT, and 500 mA IOUT, dissipation is 4.4 W - manageable with a small clip-on heatsink. For full AEC-Q100 automotive qualification, designers should instead choose an automotive-grade equivalent such as the LM7805-Q1; the LM7805ACT is appropriate for non-safety accessory loads.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho LM7805ACT — so sánh, hướng dẫn thiết kế và thông tin tuân thủ.
Hướng dẫn chọn lựa
So sánh với các sản phẩm thay thế
| Tham số | Sản phẩm này | MC7805ACTG | MC7805CTG | MC7805BTG | L7805CV | UA7805CKCS |
|---|---|---|---|---|---|---|
| Brand | onsemi | onsemi | onsemi | onsemi | STMicroelectronics | Texas Instruments |
| Package | TO-220-3 (TO-220AB) | TO-220-3 - same | TO-220-3 - same | TO-220-3 - same | TO-220-3 - same | TO-220-3 - same |
| Output Voltage | 5.0 V | 5.0 V | 5.0 V | 5.0 V | 5.0 V | 5.0 V |
| Output Voltage Tolerance | ±2% (A-grade) | ±2% (A-grade) | ±4% (non-A) | ±4% (B-grade) | ±2% | ±2% |
| Maximum Output Current | 1.0 A | 1.0 A | 1.0 A | 1.0 A | 1.0 A | 1.0 A |
| Input Voltage Range | 10 V to 35 V | 10 V to 35 V | 10 V to 35 V | 10 V to 35 V | 10 V to 35 V | 10 V to 35 V |
| Dropout Voltage (typ at 1 A) | 2.0 V | 2.0 V | 2.0 V | 2.0 V | 2.0 V | 2.0 V |
| Internal Protections | Thermal shutdown + current limit + SOA | Thermal shutdown + current limit + SOA | Thermal shutdown + current limit + SOA | Thermal shutdown + current limit + SOA | Thermal shutdown + current limit + SOA | Thermal shutdown + current limit + SOA |
Bảo phân biệt quan trọng
- A-grade ±2% output tolerance vs ±4% on standard grade (vsMC7805CTG)
- Standard 78xx pinout enables drop-in replacement across brands (vsL7805CV (ST))
- Higher peak current capability than 78L/M variants (vsMC78M05 (500 mA version))
Ghi chú thiết kế
Estimated: at VIN = 12 V, VOUT = 5 V, IOUT = 1 A, the LM7805ACT dissipates approximately (12 V − 5 V) × 1 A = 7 W. With the TO-220 θJA of ~50 °C/W (free air, no heatsink), the junction would rise ~350 °C above ambient - far above the 125 °C limit, triggering thermal shutdown. Required: a heatsink rated ≤ 10 °C/W, or alternatively a smaller load. Design rule: keep dissipation below ~2 W for TO-220 self-cooled operation at 25 °C ambient.
Place a 0.33 µF (or larger) bypass capacitor on VIN and a 0.1 µF bypass capacitor on VOUT as close as physically possible to the package pins (within 1-2 mm). For long input leads or battery sources, increase CIN to 1 µF or more. Although the LM78xx series is internally compensated and stable without an output capacitor in most cases, a small output capacitor (0.1 µF ceramic) improves transient response and high-frequency PSRR.
Do not assume any TO-220 3-pin part is pin-compatible with the LM7805ACT. The L4940 (low-dropout 5 V regulator) is NOT pin-compatible with the 78xx series despite both being TO-220 - its pinout is reversed (1=GND, 2=VIN, 3=VOUT). Always re-verify the pinout on the datasheet before substituting, especially when migrating to low-dropout LDOs. Also, do not operate the LM7805ACT above 35 V input even briefly - the pass transistor will exceed its VCEO rating and may fail.
Keep the ground tab connected to a copper pour on the PCB. For a through-hole TO-220, the tab is often soldered directly into a plated through-hole that connects to a top-side copper pad - this provides both mechanical anchoring and ~50% of the thermal dissipation. In designs that need to dissipate 5-10 W, add a 100 cm² copper pour on the opposite side of the PCB (acting as a heat spreader) connected to the GND tab via thermal vias.
Thông tin tuân thủ
RoHS-compliant and lead-free per onsemi product page. Not AEC-Q100 qualified; for automotive safety applications choose an automotive-grade equivalent. Halogen-free status not stated in the provided data.
